The present invention relates generally to the prevention of deterioration of food, cosmetic and pharmaceutical which contain polyunsaturated fatty acids. More particularly, the present invention relates to a natural composition of antioxidants for stabilization of polyunsaturated oils comprising tocopherols, ascorbic acid, citric acid, and phospholipids. The phospholipids may be derived from soybean (commercially known as "soybean lecithin") or egg or other sources. Rosemary extract can also be added to the composition.
Today, cosmetic and pharmaceutical products containing polyunsaturated fatty acids are manufactured at plants throughout the country, prepackaged for sale, and distributed to supermarkets and convenience stores across the country. Because of the nature of such products and the transportation of such products around the country, these products require a long shelf-life. In order to increase the shelf-life, it is necessary to prevent the deterioration of the quality of the product. One cause of deterioration is oxidation. Oxidation particularly occurs with fat-containing products. For example, oils and fats containing polyunsaturated fatty acids, such as fish oils which contain eicosapentaenoic acid and decosahexaenoic acid, as well as vegetable oils which contain linoleic and/or linolenic acid, are susceptible to oxidation by oxygen in the air to form peroxides. Peroxides decompose to produce volatile compounds with objectionable odors and flavors. For example, fish oil, such as menhaden oil, can quickly develop a green, grassy and fishy odor and flavor. Soybean oil is another product which can also easily oxidize to produce the classical reversion odor and flavor. In addition, such oxidation products may be harmful to human health. Even when fish oil, such as menhaden oil, is highly purified to an odorless and flavorless oil, such as that according to the teachings of Chang et al. (U.S. Pat. No. 4,874,629), the oil can still redevelop the green and fishy odor and flavor when it is exposed to even a trace amount of air or oxygen. It has been reported that fish oil, even when packaged in gelatin capsules, can develop relatively high peroxide values during storage. Furthermore, it has been reported that tocopherols alone when added to the fish oil, even when it is packaged in gelatin capsules, cannot effectively prevent the peroxidation of the oil.
Accordingly, to use such oils in food, or as a dietary supplement, they must be stabilized to prevent or to retard the development of objectionable odors and flavors, as well as to protect the health of consumers.
Many different antioxidants and antioxidant compositions have been developed over the years. Many of these antioxidants, such as BHA and BHT, are synthetic. Today, people are more health oriented and prefer natural products which are considered safe for human consumption. In addition, synthetic compounds have recently come under heavy scrutiny by the FDA. The natural antioxidant compositions, which have been developed, also suffer from problems which limit their usefulness. For example, EP 0 326 829 (Loliger et al.) discloses a natural mixture of tocopherol, ascorbic acid, and lecithin to protect lipids against oxidation. The mixture, however, may produce a red color in the oil due to the combination of ascorbic acid and lecithin.
Accordingly, it is object of the present invention to provide a composition of natural antioxidants that will retard the oxidation of fats and oils and thus the deterioration of food products. Further, it will have improved antioxidant activity over prior compounds so as to provide better prevention of oxidation and the resulting food deterioration. In addition, the present invention will significantly decrease the undesirable color that results from the combination of ascorbic acid and lecithin in the oils or their products.